This SCORE application submitted in response to the RFA from National Cancer Institute, will take advantage of the strengths in breast cancer research and treatment that exist at the Robert H. Lurie Comprehensive Cancer Center. The SPORE will provide the infrastructure to bring together basic scientists and clinicians to rapidly test new approaches in the prevention, early detection, diagnosis and treatment of human breast cancer. The specific themes of the SPORE are: 1. To investigate the role of diet and hormones in breast carcinogenesis. 2. To study the cell and molecular biology of breast cancer. 3. To evaluate factors associated with breast cancer risk and prevention. 4. To implement innovative translational therapies for breast cancer. The SPORE application consists of six principal research projects, three career development projects, five pilot projects and four Core facilities to support the research. The principal research projects are: #1. Drug resistance to anti-estrogens (PI Jordan), #2. Actions of estrogen agonists and antagonists by non-classical transcription pathways (PI Jameson), #3, Dietary and hormonal modifications of breast carcinogenesis in transgenic mice (PI Thor), #4. Estradiol levels in breast fluid, saliva and serum samples (PI Chatterton), #5. Anti-estrogens and breast density and pre-menopausal women (PI Morrow), #6 Angiostatic therapy for breast cancer: a translational study (PI Soff). The Core facilities include: Administration,, Tissue Resources, Clinical and Biostatistical Cores. The investigators selected to be part of the SPORE Program come from a variety of disciplines ranging from Clinical Programs to Chemical Engineering, Pathology and Microbiology-Immunology. To maintain meaningful communication between investigators, we will have monthly meetings of SPORE investigators, an annual retreat, monthly meetings of the Executive Committee and each investigator will be actively involved with at least one project (or core) in addition to their own. Based on the infrastructure described, our large patient population and our track record of productivity, we believe that the Robert H. Lurie Comprehensive Cancer Center is well suited for the SPORE program.